Read an article by Erik Biksa called GROWING ON THE GRID. Your setup is smaller than what he explains BUT the principals are all applicable. It improved my harvest trumendously.
You need to ask yourself a few questions...
How many plants can you legally grow? If you're not a legal grower grow less than 99 and don't worry because 1 illegal plant is as much trouble as 50 in most places.
How will you be harvesting? Larger plants are a bitch to trim alone because they take forever. Smaller plants can be trimmed up quickly so you dont have a plant sitting around half trimmed waiting for you to get home from work to finish. I can knock out two small plants by myself in an hour. Big plants take me and my buddy 8 hours to finish.
How will you be watering? Are you moving the plants often? Bigger pots are heavier to move BUT you dont need to mave as many. Smaller pots need water more often.
How tall can you get your plants? Smaller pots are quicker because you can grow them shorter an have more of them. Letting a plant get larger takes more time to grow BUT I believe the plants bloom better and are more resistant to problems when they get larger.
450-500g from a 600watt light will be a challenge for a novice grower unless you have DANK genetics and good nutrients and maybe even CO2. I have gotten 565grams from a 600 watt before. I did it like this...
5x5 hydro hut with 600watt HPS. 16, 9"x9" square pots with clones. I vegged until about 24 inches tall. I lollipopped the shit out of em and bloomed for 65 days. I fed top grade nutrients and kept my temps around 74day/68night. It took constant work keeping tiny nuggs from popping up wherr I hacked them off before but it made my colas HUGE.
I have pictures... I could have harvested better but some of my clones were shitty.
Good luck and keep us posted!
I also have a GIANT room for anyone who wants to hate on hut grows. This is my test garden before I take plants into my main rooms.